Help Please

[7 + b]^6 - 7^6

b^6 + 42 b^5 + 735 b^4 + 6860 b^3 + 36015 b^2 + 100842 b + 117649 -7^6

Sub 8 for b

262,144 + 1,376,256 + 3,010,560 + 3,512,320 + 2,304,960 + 806,736

11,272,976 = 2^4 * 11 * 13^2 * 379

15^6  - 7^6  =  {factor using  difference/sum of cubes}

(15 - 7)(15^2 + 15*7 + 7^2)(15 + 7) (15^2 - 15*7 + 49)  =

(15 - 7) (15+7)(15^2 - 15*7 + 49)(15^2 + 15*7 + 49) =

  (8)(22)(169)(379)

(2^3)(2*11)(13* 13)(379)

(2^4)(11)(13^2)(379)    is the largest prime factor

A typo of 139 should be 169.

Thanks, guest.....correction made  !!!